Age-related osteoporotic fracture is in large part due to the reduction in bone strength that occurs with age. About 80% of the variance in bone density, which is the main determinant of bone strength, is due in whites to heritable factors. Although it is known that blacks have a higher bone density and lower fracture incidence than whites, heritability of bone strength has not been studied in blacks. Identification of the genes responsible for determining bone strength within and between blacks and whites would represent a major step in early indentification of population at risk of fracture and in developing new approaches to preventative and therapeutic regimens for age-related osteoporosis.